Adding 2 more T-105 questions.
I have 2 105's that are 5 years young and would like to add 2 more. The original batteries are in mint shape. They have never been used past 60% capacity and the specific gravity is maxed out in all t...
Forum Discussion
I run a bank of 4 T-125's as one single bank and really like the simplicity and advantages. As long as the batteries are reasonably matched, shouldn't have a problem.
If old and new SG is close to the same I'd get a harbor freight battery load tester and using Mex's guidelines for 6V do a load test on old and new. If the results are reasonably close, I'd wire them as a single bank of 4.
Why?
1) if you run a heavy inverter load, voltage drop won't get you an undervoltage alarm (50+A)
2) under what may be "typical" discharge, you may actually gain useable AH vs. a bank of two. for a "typical" 5-10A draw, looking at Trojan data, you'll be near 500AH since your closer to a 40H rather than 20H discharge rate.
3) it's easier to wire, and can use a simpler battery disconnect switch.
4) you can run at least twice as long before needing to mess with anything.
5) when you do need to charge it's quicker both getting to a 90% or so SOC and getting to full charge than charging individual banks seperately.
Here is what I recall Mex suggesting for GC battery load test. test each battery individually, not wired in series as a 12V bank
220A for 20 seconds and measure voltage under load at 20 seconds. IIR you should see 5.5-5.6V on good batteries.
if the load test results are drastically different, then I'd wire them as two banks.
If old and new SG is close to the same I'd get a harbor freight battery load tester and using Mex's guidelines for 6V do a load test on old and new. If the results are reasonably close, I'd wire them as a single bank of 4.
Why?
1) if you run a heavy inverter load, voltage drop won't get you an undervoltage alarm (50+A)
2) under what may be "typical" discharge, you may actually gain useable AH vs. a bank of two. for a "typical" 5-10A draw, looking at Trojan data, you'll be near 500AH since your closer to a 40H rather than 20H discharge rate.
3) it's easier to wire, and can use a simpler battery disconnect switch.
4) you can run at least twice as long before needing to mess with anything.
5) when you do need to charge it's quicker both getting to a 90% or so SOC and getting to full charge than charging individual banks seperately.
Here is what I recall Mex suggesting for GC battery load test. test each battery individually, not wired in series as a 12V bank
220A for 20 seconds and measure voltage under load at 20 seconds. IIR you should see 5.5-5.6V on good batteries.
if the load test results are drastically different, then I'd wire them as two banks.
